He took the time to write what he did, and didn't like, about the plugin and why he chose to fix it. Read his entry where he introduces Slugger .
To me, this is the perfect example of why I love writing these little plugins. I may not personally be the best person to write some of these plugins (due to my inability to watch for things as detailed as someone like Justin obviously is), but I did have the idea and at least I was able to "get it out there" so other people could improve on it.
And that is exactly what Justin has done. He took what he thought was a good idea for a WordPress plugin, fixed what needed to fixed, and offered a better version of it to everyone for free.
Thanks for updating the plugin Justin. I'll use it religiously.